Conditionally update an the object stored under \code{key} in \code{space}.
Existing values will be overwritten with the values specified by \code{attrs}.
Values not specified by \code{attrs} will remain unchanged.  If the object
exists, this is equivalent to a \code{cond\_put}.  If the object does not exist,
this is equivalent to a \code{put}

\input{\topdir/client/fragments/conditional}
